The difference between reptilian eggs and amphibian in that eggs?

Here's a breakdown of the key differences between reptilian and amphibian eggs:

Reptilian Eggs:

* Shell: Tough, leathery or hard (depending on species) shell for protection.

* Yolk: Abundant yolk provides nourishment for the developing embryo.

* Amnion: A membrane surrounding the embryo, creating a fluid-filled sac that cushions and protects it.

* Allantois: A membrane that stores waste products from the embryo.

* Chorion: A membrane that allows for gas exchange (oxygen in, carbon dioxide out).

* Development: Internal fertilization; eggs laid on land (except for some sea turtles).

* Environment: Typically laid in nests or buried in sand, allowing for incubation at a relatively stable temperature.

Amphibian Eggs:

* Shell: Lack a hard shell, often encased in a gelatinous layer for protection.

* Yolk: Less yolk than reptilian eggs, as embryos may hatch earlier and are often nourished by external sources.

* Amnion: Absent; embryos are directly exposed to the surrounding environment.

* Allantois: Absent; waste is excreted directly into the environment.

* Chorion: Absent; gas exchange is primarily through the jelly-like coating.

* Development: External fertilization; eggs laid in water or moist environments.

* Environment: Highly dependent on water for development and to prevent dehydration.

Summary:

* Shell: Reptilian eggs have a protective shell, while amphibian eggs lack a true shell and are enclosed in jelly.

* Amniotic Egg: Reptiles have an amniotic egg (amnion, allantois, chorion) which allows for development on land. Amphibian eggs lack this adaptation and require a water-dependent environment.

* Yolk: Reptilian eggs have a larger yolk sac for sustained development, while amphibians rely more on external sources.

The key difference boils down to the amniotic egg, which is a major evolutionary adaptation that allowed reptiles to successfully colonize land. Amphibians, lacking this adaptation, are still tied to water for at least part of their life cycle.